In modern and future communication systems, including both mobile and fixed networks, which are typically IP based, there are trends of traffic offloading and flow mobility. Operators are interested in offloading IP traffic from one access type or technology (such as a cellular network) to another access type or technology (such as a local network, e.g. an enterprise network), but typically still in such a way that IP traffic is carried via the operator core network. To this end, IP traffic flows are subject to mobility in terms of a switching of traffic routes due to offloading in the range between the host (e.g. UE or MN) and the operator core network, especially the operator gateway. A main motivation for traffic offload and flow mobility is the vast increase of data traffic in the past years that has pushed operator networks, especially cellular or MNO network, to their limits in terms of data/radio throughput and performance.
Both 3GPP and IETF have defined their own specifications for traffic offloading and flow mobility in the context of traffic offloading. The current specifications are however based on a concept of switching IP traffic flows between individual interfaces or (access) connections of the host, meaning that also the access type or technology is switched.
As an example, there is an IETF draft for Proxy Mobile IPv6 Extensions to Support Flow Mobility. This proposal however assumes that the IP host has two different interfaces connected to at least two separate networks each hosting its own MAG functions. Traffic flows are switched between access connections of the host, i.e. between different host interfaces or (access) connections corresponding to different MAG functions.
As another example, 3GPP and IFOM specifications introduce approaches for flow mobility, which are built on the basis of DSMIPv6 and PMIPv6. MAPIM and IFOM also assume two different interfaces, i.e. two different access types or technologies, to two separate networks each hosting MAG functions of their own, and the traffic flow switching is done between the interfaces or (access) connections of the host, thus corresponding to different MAG functions.
As still another example, SIPTO is a 3GPP feature in which part of the traffic is offloaded from the MNO's transport network to another PDN below the P-GW which is located in the MNO's core network. SIPTO is based on multiple PDN connections, wherein a new PDN connection is established to the properly located offloading GW (such as GGSN or P-GW). However, traffic flow mobility is not possible with SIPTO, since an IP attachment point of the new PDN connection is different as compared with the initial PDN connection. Moreover, the establishment of a new PDN connection requires lots of signaling and, since logically from the host's perspective the SIPTO connection is separate, an IP interface with an own set of IP addresses. Thus, traffic offloading with SIPTO is subject to significant signaling efforts and is not transparent to the host.
While such concepts are reasonable with legacy systems, i.e. legacy radio types and technologies, with limited data/radio throughput and performance, they are not effective for modern and future communication systems.
With the introduction of LTE and especially LTE-A and beyond 4G radios (with radio throughput of 10 Gbit/s), there arises a new situation in that the radio part is not anymore such a bottleneck of the overall data path. As building the transport network to meet the increased radio capacity of the radio part is expensive, thus the possibility to offload traffic out of the transport network while remaining within a single access type or technology, i.e. the same host interface or (access) connection, is desired.
Accordingly, it is desirable to enable traffic flow mobility with a single host connection.